Best way to use mini split heating heat pump?

[h2ofun]

Do your mini-splits have electric resistance heating for low temps or are they strictly heat pumps?

I do not believe mine have any heat strips, mits, So far coldest outside is mid 30's

 

[getakey]

I do not believe mine have any heat strips, mits, So far coldest outside is mid 30's

when I replaced my gas furnace, I got a heat pump with gas as the emergency heat since gas was already plumbed there. The additional advantage is that during power outage I can switch it to gas and save heat pump draw from the powerwalls

 

[h2ofun]

when I replaced my gas furnace, I got a heat pump with gas as the emergency heat since gas was already plumbed there. The additional advantage is that during power outage I can switch it to gas and save heat pump draw from the powerwalls

I had looked into that but do not believe they came in mini splits. I have my generator if needed. They do not last long enough to really worry about. I just got a call we may get one on Dec 7th power outage

 

[Sealander]

The last comment of this post has the right answer (direct link below):


For example, from a pure physics perspective looking at just heating, your outdoor compressor is most efficient when it's warm outside - and do you really need or want the same temperature inside from 2-5 AM when you're sleeping and it's at it's coldest outside? Also, the indoor heat exchanger is also more efficient when pulling in cooler air to warm up - it's able to transfer more heat to the air for a given airflow.

That where zoning really comes into play. You can keep the bedroom at a different temperature than other parts of the house and do not necessarily have to keep adjusting the temperature in each zone.

 

[h2ofun]

That where zoning really comes into play. You can keep the bedroom at a different temperature than other parts of the house and do not necessarily have to keep adjusting the temperature in each zone.

I have 10 heads in my house, basically 100% zoning. From my tests and research, one just needs to let go of how one used furnace systems with gas since the new heat pumps work the best when left set and on all day long. I have 5 of my 10 now set at 61 and will run them that was 7/24 for least overall cost, and best comfort. I let my bedroom get to the mid 50's one night when I turned off thinking I was going to save money. I did not sleep worth beans because my face was freezing.

 

[getakey]

Do you really like having your house at 61? As I said before, with that many panels and not consuming more electricity in the winter, your annual true up may be very negative. If that is the case, you will probably regret keeping the house so cold

 

[solarAddict]

Okay, since so many are doing things to save electric costs, looking for some guidance.

I live in about 4500 sq foot house, 2 plus levels. Used to have 2 propane multipack systems.
To make a long story short, these were removed and replaced with new mini split heating cooling systems, 10 heads
throughout the house. I love the ability do to real zoning.

But, since my solar is down to like 25% of what it produces in the summer, trying to figure out the best way to run these new mini splits for the least cost, but being able to keep my large home warm. It is 60 now.

With the propane heating, I would only run when needed, so this is how I am currently mentally programmed.

But, with the mini split heat pumps, is this the correct way to use? I have read some opinions that I should just set the temperature, like at 64, and let them run 7/24 to use minimum electricity?

But then I am thinking do they cost more to run in the morning, when my outside temps are 30? Meaning, should I turn off and lets say turn them on at 2 pm, and heat up the house to lets say 70, and then turn them off at 7 pm when I go to bed?

Thanks for any advice on best way to use these.

Do you have a programmable t-stats for baseboard heat system? If not - highly recommended. Easy reduce the temp after you go so sleep and pre-heat the room/s before everyone wakes up.
Also it your split system is controlled by remote only I would suggest to add a pseudo -smart thermostat, basically wifi bridge. you can create a schedule, control device from your phone etc. It's not 100% convenient as a say Nest but it's a big step up from the remote..
I use Ciello Breez Plus.

 

[h2ofun]

Do you really like having your house at 61? As I said before, with that many panels and not consuming more electricity in the winter, your annual true up may be very negative. If that is the case, you will probably regret keeping the house so cold

My wife LOVES it being cooler. The choice of temp set is hers. Told her last night this is fine since I just wear my long underwear in the winter.

Now with that said, I will just keep collecting data, and see how the year goes. I still might change things next year after I know what my true up is in July. But, since she likes it cooler, keeping the house in the summer at 70 night be where she wants to spend the money.
And with the size of my house, and big upstairs valeted ceilings, keeping my house cool is very expensive!!!

 

[h2ofun]

Do you have a programmable t-stats for baseboard heat system? If not - highly recommended. Easy reduce the temp after you go so sleep and pre-heat the room/s before everyone wakes up.
Also it your split system is controlled by remote only I would suggest to add a pseudo -smart thermostat, basically wifi bridge. you can create a schedule, control device from your phone etc. It's not 100% convenient as a say Nest but it's a big step up from the remote..
I use Ciello Breez Plus.

No baseboard heat.

I have looked into adding the smart thermostat stuff to my mits mini splits. But since it costs about 500 bucks per head, and I have 10, .....

Again, since the data I have seen says just set the temp and run 7/24, I see no reason to do anything differently. What am I missing?

 

[zƬesla]

I do miss using my baseboard with programmable thermostats as I found it to keep a more even heat when it's freezing out than the 5 mini-split heads. Once I have the RPi developed (initial prototype successfully tested last weekend!), I may play around with temp settings, however really just want it to auto shut off heads in winter during a grid outage to keep PWs from draining too fast.

 

[h2ofun]

I do miss using my baseboard with programmable thermostats as I found it to keep a more even heat when it's freezing out than the 5 mini-split heads. Once I have the RPi developed (initial prototype successfully tested last weekend!), I may play around with temp settings, however really just want it to auto shut off heads in winter during a grid outage to keep PWs from draining too fast.

Keep us informed on your testing status. What have you developed and how does it work. So far my mini split heads seem to work great and keep the house at the temp I set at.

 

[SSedan]

Do your mini-splits have electric resistance heating for low temps or are they strictly heat pumps?

Strictly heat pump. Far as I know the only resistance heat is in the drain pan under the coil They actually periodically run the AC to defrost the coil by using heat from the house.

This is an expensive setup, but saved me having to either run a boiler in conjunction or tear apart the finished basement to run soffit around ducts.
I have 3 outdoor units 5 indoor 12k BTU and one 18k BTU, left the baseboard electric in the bathrooms.

 

[solarAddict]

No baseboard heat.

I must be confused two posts in one: yours and zTesla's. as I have similar setup (oil boiler/ HW baseboards - 3 zones - for 2 floors, and minisplit for attic master). I hate air heating upstairs and thinking to add heater floor to entire level, luckily it's small. Hope my new PV setup will help me offset the cost.

I have looked into adding the smart thermostat stuff to my mits mini splits. But since it costs about 500 bucks per head, and I have 10, .....

Again, since the data I have seen says just set the temp and run 7/24, I see no reason to do anything differently. What am I missing?

I'm in MA and here National Grid (electric provider) running promo campaigns through MassSave for smart thermostats. Like this one:
https://www.poweredbyefi.org/masssave/google-nest-thermostat-snow.html

I see few advantages in using smart thermostats:
- ability to control temp from the phone, including remotely. you left for long weekend and forgot to put the system in "vacation" mode. No big deal, do it from the road. Coming back - just bump up the temp few degrees just few hours before getting there.
- preprogramming that fit your schedule. Lower temp when you sleep. preheat before sunrise, lower temp in bedroom when you are not there during the day.
- tweaking temp room by room. etc.

 

[Dave EV]

I'm in MA and here National Grid (electric provider) running promo campaigns through MassSave for smart thermostats. Like this one:
Google Nest Thermostat Snow

The problem is that most mini-splits can't use your typical replacement "smart thermostat", they're unique. Most aftermarket thermostats can only handle your typical 1-2 stage HVAC system.

For example, I have a Trane communicating dual-fuel system (heat pump + gas furnace) with a basic programmable, and you can only use special Trane thermostats which cost a fortune.

Mini-splits usually have an infrared remote for each head that you use to control the system.

 

[h2ofun]

The problem is that most mini-splits can't use your typical replacement "smart thermostat", they're unique. Most aftermarket thermostats can only handle your typical 1-2 stage HVAC system.

For example, I have a Trane communicating dual-fuel system (heat pump + gas furnace) with a basic programmable, and you can only use special Trane thermostats which cost a fortune.

Mini-splits usually have an infrared remote for each head that you use to control the system.

Yep, the default mits remote does not have any programmable features. Ones needs to purchase their unique hw per head at 500 bucks per head to control. Would love to have the toys but for close to 5K to put in my ten heads, would take a while to pay back, if ever.

 

[zƬesla]

What have you developed and how does it work.

It’s a Raspberry Pi 0w that plugs into the same connector as the $200 Mitsubishi WiFi addon. For about $20 in parts instead, it lets me control the mini split head via a web API I’m coding. It’s initially set up to power off the head automatically if the grid goes out, but only in winter when it uses a lot of energy. I’ll likely let it run in summer for AC as that doesn’t take anywhere near the same amount of energy for us. There’s full control of the unit via the API or a web page, such as temp/vane/fan changes, so I can also turn it into a smart thermostat and use remote temperature sensors for better performance; one unit is high up a 2-story wall, so temp reading is usually a bit off.

 

[h2ofun]

It’s a Raspberry Pi 0w that plugs into the same connector as the $200 Mitsubishi WiFi addon. For about $20 in parts instead, it lets me control the mini split head via a web API I’m coding. It’s initially set up to power off the head automatically if the grid goes out, but only in winter when it uses a lot of energy. I’ll likely let it run in summer for AC as that doesn’t take anywhere near the same amount of energy for us. There’s full control of the unit via the API or a web page, such as temp/vane/fan changes, so I can also turn it into a smart thermostat and use remote temperature sensors for better performance; one unit is high up a 2-story wall, so temp reading is usually a bit off.

very cool. Got a picture of how you connected?

 

[solarAddict]

The problem is that most mini-splits can't use your typical replacement "smart thermostat", they're unique. Most aftermarket thermostats can only handle your typical 1-2 stage HVAC system.

For example, I have a Trane communicating dual-fuel system (heat pump + gas furnace) with a basic programmable, and you can only use special Trane thermostats which cost a fortune.

Mini-splits usually have an infrared remote for each head that you use to control the system.

Yep, the default mits remote does not have any programmable features. Ones needs to purchase their unique hw per head at 500 bucks per head to control. Would love to have the toys but for close to 5K to put in my ten heads, would take a while to pay back, if ever.

I posted the solution for this issue in my original post. These devices work with variety of heating/cooling devices (if you r device has IR remote it will work for you):

.

There several different brands to choose from. It's not ideal but pretty close to real smart thermostat for a fraction of the cost.

 

[h2ofun]

I posted the solution for this issue in my original post. These devices work with variety of heating/cooling devices (if you r device has IR remote it will work for you):

.

There several different brands to choose from. It's not ideal but pretty close to real smart thermostat for a fraction of the cost.

Wow, that looks super cool. At that price I may need to buy 10

 

[zƬesla]

very cool. Got a picture of how you connected?

Pictures attached showing the unit open with connector used circled, and innards of prototype #2. Looking for a small white enclosure (box) for mounting on the side or under the unit. The parts are also small enough they could just go inside the unit but I want access without having to open the unit back up.